Ethereum’s Fusaka Upgrade Activated on Sepolia Testnet

Ethereum’s Fusaka upgrade has been activated on the Sepolia testnet, marking the next major step in the network’s ongoing push to improve scalability and performance.

The upgrade is the second phase of a three-step rollout under Ethereum’s Fusaka roadmap, following the Holesky testnet activation on October 1. The Sepolia deployment focuses on stress testing the network’s new capabilities.

Since larger blocks result in nodes processing and storing more data, Peer Data Availability Sampling (PeerDAS) is also being tested. PeerDAS lets Ethereum validators verify transaction data by sampling small pieces from multiple peers instead of downloading everything, enhancing speed and scalability while maintaining decentralization.

Paul Harris, a Fusaka core developer and protocol engineer at Consensys’ Teku client, mentioned that with PeerDAS, validators no longer need to store all network data, significantly reducing the burden on nodes. “Fusaka changes how data availability is done, enabling scaling beyond what was possible before PeerDAS,” Harris stated.

The Ethereum Foundation unveiled the Fusaka testnet schedule on September 26, outlining the final steps before the network’s next major upgrade. Fusaka follows this year’s Pectra update, with its final trial on the Hoodi testnet set for October 28 and a mainnet launch expected in December.

A Brief History of Ethereum Upgrades

Since its launch in July 2015, the Ethereum network has undergone several major upgrades to improve scalability, security, and performance.

The most recent upgrade took place on May 7, when the Pectra update went live, introducing three key improvement proposals. Among the changes, Pectra enabled externally owned accounts to function like smart contracts and pay gas fees in tokens other than ETH, raising the validator staking cap to 2,048 ETH from 32 ETH, and expanding the number of data blobs allowed per block.

Before Pectra, Ethereum rolled out the Dencun upgrade on March 13, 2024, drastically reducing gas fees on the network. Within one year after Dencun, the average gas fees on Ethereum dropped by as much as 95%.

Perhaps the most famous Ethereum upgrade is known as The Merge, which occurred in September 2022 and transitioned Ethereum to a proof-of-stake blockchain from a proof-of-work blockchain, ending mining and introducing validators, with energy costs reduced by up to 99%.

The Shanghai upgrade in April 2023 was also a critical step for the network’s roadmap, allowing validators staking Ether (ETH) to make withdrawals for the first time, completing Ethereum’s transition to proof-of-stake.